I Don't Think So
1UU
Instant
Reveal your hand. If no creature cards are in it, counter target spell."As if..."

Never Trust a Blue Mage
2UU
Enchant Creature
Enchanted creature has flying and can't attack.
UU: Return Never Trust a Blue Mage to its owner's hand.How can you tell when a blue mage is lying?He opens his mouth.

Undercover Disguise
4U
Enchant Creature
You may play Undercover Disguise any time you could play an instant.
As Undercover Disguise comes into play, choose a creature type. Enchanted creature is that type.

Mutated Cockroach
4BBB
Creature - Mercenary Insect
5/4
At the beginning of your upkeep, target opponent chooses a color other than black. You sacrifice all creatures of the chosen color."It was the size of a house. No really."

Being an Evil Minion Sucks
3BB
Sorcery
As an additional cost to play Being an Evil Minion Sucks, sacrifice a creature. Destroy target creature other than a Wizard. If Volrath ever summons you by name, run!- Stronghold graffitti

Avalanche of Squirrels
4GG
Creature - Squirrels
3/3
Echo (At the beginning of your next upkeep after this permanent comes under your control, sacrifice it unless you pay its mana cost.)
Avalanche of Squirrels can't attack if a Goblin or Insect is in play.

Bunch of Elephants
7GG
Creature - Elephants
8/8
Trample
Sacrifice a permanent: Prevent all damage Bunch of Elephants would deal this turn. Any player may play this ability."Sure I've heard of elephants..."